1. Field
Embodiments of the present invention relate to a wireless communication system, and more particularly, to an apparatus and a method for transmitting and receiving a cyclic shift parameter for supporting orthogonality in a Multiple Input Multiple Output (MIMO) environment.
2. Discussion of the Background
With the development of communication systems, a wide variety of wireless terminals are being used by consumers, such as business companies and individuals.
Current mobile communication systems, such as 3GPP (3rd Generation Partnership Project), LTE (Long Term Evolution), and LTE-A (LTE Advanced), may bring forth the development of technology for a high-speed large-capacity communication system, which can transmit or receive various data, such as images and wireless data, and thus beyond the capability of mainly providing a voice service, and can further transmit a large capacity of data in a wired communication network. Moreover, the mobile communication systems are being used with a proper error detection scheme, which can minimize the reduction of information loss and improve the system transmission efficiency, thereby improving the system performance.
Further, in various communication systems, various Reference Signals (RSs) are used to provide information on a communication environment, etc. to counterpart devices through an uplink or a downlink.
For example, in a Long Term Evolution (LTE) system, which is an evolved system for mobile communication, a User Equipment (UE) transmits an Uplink Demodulation Reference Signal (UL DM-RS) as a reference signal in each slot in order to obtain channel information for demodulation of a data channel at the time of uplink transmission. Further, a sounding reference signal is transmitted, as a channel estimation reference signal indicating the channel state of the UE, to a base station (eNodeB) transceiver, and a Cell-specific Reference Signal (CRS) is transmitted at each sub-frame in order to obtain channel information at the time of downlink transmission.
The reference signals as described above may be generated and transmitted by a UE if they are uplink reference signals and are generated and transmitted by a base station (eNodeB) transceiver if they are downlink reference signals.
Further, in the case of an uplink, reference signals are generated by generating a plurality of sequences through complex dimensional phase shifting using a predetermined cyclic shift.
However, there has been a recent demand for the use of more extended reference signals or sequences, in order to secure the flexibility of communication systems, etc.